There is a concept of classes which the nouns should belong. Also, possessive pronouns, adjectives etc have to agree with the class of the noun. For example, here "mzazi" belongs to the m - wa class , so the possessive has to be "wangu" to agree with the class of mzazi for the corresponding English "my".
If the example had been "My book ... ", the Swahili would have been "Kitabu changu ..." and "My books ..." would be "Vitabu vyangu ..." . Notice the pattern. I hope that helps.
I wouldn't say that dada and kaka are in the M/WA class, since their singular and plural forms are identical, and they agree with verbs like N/N nouns. Wiktionary says "dada (n class, plural dada)". I find it weird that they don't get M/WA agreement on the basis of being animate (N/N animals do), but that's the way it is.
Also, not all Arabic-derived words for people are like this; mwalimu comes from Arabic! (It's probably helped by the fact that the original Arabic verb starts with mu-, so it's a pretty short step for Swahili to reanalyze the Arabic form II active participle as having an M/WA prefix, especially since it describes a person. A similar thing happens with kitabu, where the k is an integral part of the Arabic root, but in Swahili it becomes part of the prefix.)
The prefix of ake need s to agree with the noun mzazi and the agreement for this noun class is w, so its wake this link may help https://www.google.com/url?sa=t&source=web&rct=j&url=https://www2.ku.edu/~kiswahili/pdfs/lesson_45.pdf&ved=2ahUKEwis9rzb8fDiAhWVQhUIHfzHDdcQFjAAegQIAxAB&usg=AOvVaw3M_cT88nXSN41Bf7_VRfUH